The present invention is a method of manufacturing siloxane or silane compounds which contain acyloxy groups which are important for efficient treatment of surfaces of inorganic solid bodies, for introduction of functional silyl groups or functional siloxanoxy groups into siloxane polymers, organic polymers, or similar polymers, as well as for use as functional groups of siloxanes curable by atmospheric moisture.
Polymers or compounds having silyl groups directly bonded to hydrolyzable functional groups such as alkoxysilyl groups, chlorosilyl groups, etc., find important industrial application as modified silicone-type raw materials used for treating surfaces by hydrolyzing the functional groups followed by the formation of siloxane bonds by dehydration and condensation, or for curing by formation of cross-linking bonds between polymers. As a rule, silyl groups having hydrolyzable functional groups, such as alkoxysilyl groups, chlorosilyl groups, etc., are produced by hydrosilation of unsaturated organic compounds or polymers having unsaturated groups with hydroalkoxysilanes, or hydrochlorosilanes. However, such reactions of hydrosilation of the aforementioned hydrosilane compounds are often characterized by a slow reaction rate, requires a large amount of catalysts, and takes considerable time. Typically, such reactions have poor selectivity and the product is produced as a mixture of isomers. Furthermore in order to maintain catalytic activity, hydrosilation reactions with hydroalkoxysilanes or hydrochlorosilanes often require the presence of oxygen. This is dangerous because it may cause explosion or fire.
Japanese Laid-Open Patent Application (Hei) 9-31414 describes hydrosilation of a vinyl group which is present in polyimide formed by reacting tetracarboxylic acid dianhydride and a diaminopolysiloxaneo having a side vinyl group. The aforementioned hydrosilation reaction is conducted with the use of a hydrosilane represented by the following formula: X.sub.3-t SiH(R.sup.9).sub.t, where R.sup.9 is an alkyl group having 1 to 6 carbon atoms, X is a hydrolyzable group, except for an alkoxy group, and t is an integer from 0 to 2. Examples of the aforementioned hydrosilanes are methyldiacetoxysilane and triacetoxysilane. Practical examples of the aforementioned publication refer to the use of methyldiacetoxysilane. The present inventors have unexpectedly found that the aforementioned methyldiacetoxysilane and triacetoxysilane possess extremely poor hydrosilation activity with respect to various olefin-type unsaturated compounds and acetylene-type unsaturated compounds, as well as to polyimides having olefin-type unsaturated side groups. In other words, it was unexpectedly found that hydro (monoacyloxy)silanes possess extremely high activity with respect to the last-mentioned olefin-type unsaturated compounds and acetylene-type unsaturated compounds.
It is an object of the present invention to solve the problems associated with hydrosilation involving the use of the aforementioned hydroalkoxysilane, hydrochlorosilane, or hydrodiacyloxysilane and hydrotriacyloxysilane, more specifically the problem associated with low activity during the hydrosilation reaction. Another object is to solve the problem associated with low regio-selectivity in the aforementioned reaction. More specifically, it is an object of the present invention to provide a method for performing the hydrosilation reaction efficiently and economically with regard to the reaction time and catalyst activity, as well as to improve regio-selectivity in the reaction. Another object of the invention is to make it possible to conduct the hydrosilation reaction in an inert environment and under low oxygen partial pressure due to high catalytic activity and extended catalyst activity, thus reducing the danger of explosion and fire in conducting the hydrosilation reaction.
The present inventors have found that silyl compounds can be produced with high yield at a high reaction rate and with high position selectivity by producing functional silane compounds by carrying out a hydrosilation reaction with the use of a platinum catalyst between Si--H functional silane compounds and various olefin-functional or acetylene-functional unsaturated compounds (the aforementioned compounds differ from polyimides derived from diaminopolysiloxane having olefin-type unsaturated side groups). The aforementioned effects are achieved by having in the aforementioned Si--H functional silicon compound one acyloxy group bonded directly to the aforementioned silicon atom. It has been found that the above-described hydrosilation reaction can be rapidly carried out under low partial oxygen pressure or without the presence of oxygen.